A. Field of the Invention
This invention relates, in general, to electrostatic ink jet printers and, in particular, to an ink jet printer cartridge having an ink jet nozzle of a predetermined length which cartridge provides a low-head pressure, high flow, single filament ink jet that delivers fluid ink to a point in a controlled manner.
B. Prior Art
In the past, electrostatic ink jets used a long tube as the jet nozzle. This long nozzle length restricted fluid flow due to viscous drag. To increase this ink flow, the head height of the ink surface could have been increased, but this increase not only caused dripping of ink out of the jet nozzle tip but caused frequency response problems as well. Likewise, the increase in ink flow could have been obtained by using a larger diameter ink jet or a lower viscosity ink. In the case of the larger diameter jet, control problems were created, whereas low viscosity inks were difficult to develop.
Another problem that existed in the past was the limitation of the writing voltage that could be applied. This maximum writing voltage was determined by the point where a pair of filaments appeared on the ink meniscus. These filaments leave the nozzle at two points where the voltage gradients are the same. This limited the voltage that could be applied for control of the ink.